What is a DUCR? Format and example

TL;DR

Quick definition

If a UK agent asks: "What is your Dooker?", they mean DUCR. In the system GVMS often DUCR (or MRN) is entered to link the declaration with the vehicle. `4GB123456789000-12345`. Format: `Year` + `GB` + `EORI` + `-` + `Trader's Own Reference`. It is the main identifier in British export.

DUCR is the British equivalent of the shipment reference number. It is the main identifier in British export. Format: `Year` + `GB` + `EORI` + `-` + `Trader's Own Reference`. E.g. `4GB123456789000-12345`.

In the system GVMS often DUCR (or MRN) is entered to link the declaration with the vehicle. If a UK agent asks: "What is your Dooker?", they mean DUCR.

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What the current official guidance means in practice

For operational work, the current procedural rules, declaration fields and relief conditions should be checked directly against the official guidance. For this topic, the core reference points are GOV.UK / HMRC.

Operational watch-outs

Most delays come from inconsistent data between the commercial invoice, packing list, tariff classification, reference numbers and transport assumptions. Before shipment release, confirm who is responsible for clearance, whether the data set is complete and when the declaration must be filed.

Documents and data to prepare

The minimum working pack worth preparing before speaking to customs support or filing a declaration includes:

commercial invoice with a complete goods description
packing list with quantities, weight and package count
HS/CN code and origin information
EORI number and the party responsible for the declaration

Practical notes for UK-PL operators

For regular flows, keep a stable data template: goods description, HS code, origin, Incoterms, carrier details and source documents. This shortens response time and reduces border corrections.

Official sources

GOV.UK: Declaration Unique Consignment References (DUCR format) — GOV.UK / HMRC, 2026-09-10
GOV.UK: Get a goods movement reference (which reference each route needs) — GOV.UK / HMRC, 2026-09-10
GOV.UK: Customs Declaration Service — GOV.UK / HMRC, 2026-03-04

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FAQ

What does DUCR stand for?

DUCR stands for Declaration Unique Consignment Reference. It is the reference that identifies a single consignment on a UK customs declaration and ties the declaration to the commercial paperwork behind it. HMRC guidance requires the trader to be able to guarantee that each DUCR is unique.

What is the format of a DUCR number?

A DUCR follows the World Customs Organisation structure and can be up to 35 characters long. For a UK trader it is built as year + GB + EORI + a dash + the trader's own reference, for example 4GB123456789000-12345. The final component is up to 18 characters devised by the trader whose EORI appears in the DUCR, restricted to digits, capital letters and a limited set of special characters — forward slashes must not be used.

What is the difference between a DUCR and an MRN?

The DUCR is created by the declarant or their customs agent before the declaration is submitted, and identifies the consignment. The MRN is issued by the customs system once the declaration has been accepted, and identifies that declaration movement. In short: you devise the DUCR, HMRC gives you the MRN. See our guide to what an MRN is and where it is used.

Do I need a DUCR to create a GMR in GVMS?

It depends on the movement. For goods leaving Great Britain for the EU, GOV.UK guidance says the goods movement reference must carry the DUCR for the combined customs and safety and security export declarations; the same applies to a combined declaration on a Northern Ireland to Great Britain movement. Other routes are keyed on an MRN, an EORI number or a carnet reference instead. Our overview of GVMS, GMR, ENS and EXS on the UK-France route sets out which reference belongs where.

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What is DUCR (Declaration Unique Consignment Reference)? [2026]